I was looking at an 02 Excursion V10 at a dealership, 92K miles. When we started it up, let it idle, I got in for a test drive and the check engine light was on, as well as trans o/d light blinking. Salesman was embarrassed, said they had fixed that. I drove it, it was fine, the od blink went away as soon as the truck started moving, 5mph or so, basically. I left, they took it back to the mechanic, who installed a brand new ford valve body, but couldn't get the check engine light and blinking to stop. Called a trans place, he told him to clear the codes, in the TCM I assume. Said it was good after that, a mechanic drove it home 72 miles for a test, then another guy drove it around, salesman said it was fixed. I drove back down 2 hours to buy the truck, he starts it up, both lights are on/blinking again! Another test drive, nothing funny. So I talked them down $2500, saying that I will need to put a new tranny in it. Brought it home, 125 miles or so, it ONLY blinked on startup, until I got moving, never came on again, I don;t think it even came back on idling hot in my driveway. Trans worked perfectly the whole way, I was inpressed with the shifting actually, compared to my 2000 Ex V10.
Does this ring a bell with anyone? Low oil pressure at idle, bad sensor, bad oil pump at cold idle, plugged oil filter? This tranny DID have a leak problem, into the t-case, which was the original thing that was fixed, but no cooked fluid and it seems good. I will take it down and get it scanned, I have $2500 to fix the problem, but if anyone has seen this before, lmk so I can fix it and save the scan! I can clear the check engine light with my superchips. (I only use it for code reading.) I really think the tranny is fine, it is just something small/easy.
Chris

 

Pull the fault codes - anything else is just guessing. Less than $200, you can buy a decent enough scan tool to do the job.

 

That won't cause the light to flash.
This could.
This will not.
If this is your problem (and that's unlikely) you need a new transmission. The only way the filter can get plugged is when the transmission fails.

As was said the ONLY way to know what's wrong is to get the codes read. Without reading the codes you could replace the transmission and still have the same problem! The problem may or may not be inside the trans, it could be many items outside of the trans.

 

Gotcha. I thought that you needed a Ford dealership to read TCM codes, while any cheapo obd scanner can read regular ones?

 

No, no cheap OBDII scanner can read Ford transmission codes. It takes a fairly high end scan tool with Ford specific software. Many independent shops can read them, and all Ford dealers. I've never found an auto parts store that could.

 

Hmm. I just hooked up my Superchips, gave me three codes:
01 - P1702 trans range sensor/wiring
02 - P0708 trans range sensor/wiring
03- P1000 needs more driving
Sounds like I need to crawl under, unplug that range sensor, clean things up, check for damaged wiring, put it all together, clear the codes and see what comes up?

 

That is a good first step. If the problem is still there the next step would be to electrically check the wiring.

 

So, here are some fun facts. ONLY blinks in park. Start in neutral, no blink. Put it into park, wait ten seconds, blink, put it into drive and wait 10 seconds, no blink. Not once has blinked except in park, hot or cold.

 

That correlates to a problem with either the TRS or the wiring harness connected to the TRS.

 

Which jives with the codes I pulled. Going to go crawl under it now and take a looky look. Are those sensors adjustable? I cannot remember, I seem to recall messing with one on my 2000 Ex, but I don't remember. I could maybe rob the one from my 00 if they are the same and swap, but seems easier to just buy a new one if the wiring checks out, as they are fairly cheap.

 

It isn't an adjustment problem. The codes say there are electrical circuit problems.

 

Makes sense. I just pulled it off, checked the connectors and the unit, all look great. No damaged wires up as far as I could check from the bottom, they are still in the factory clips/etc., but we are having a rain storm, so quit messing with it after I reinstalled it. Problem still there, I would bet it is the sensor itself. Any way to check the wiring back to the pcm or wherever they go? Any chance of a PCM issue? Actually, as easy as they come off, I SHOULD just swap the one out of my other Ex. I will check to see if they are the same part numbers.
I do appreciate the help Mark!
Chris

 

Visually checking the wiring is only the first step. You need to electrically check each circuit from the PCM to the TRS.

NEVER put a probe into the pins. That spreads them and causes a new problem. Always probe from the back side of the connectors.

There is a chance it is a PCM issue. Probably one out of 10,000 is a bad PCM. All the others are either a wiring problem or a bad TRS. Usually the wiring.

 

That sounds like no fun. Gonna have to find a decent manual for this thing I guess, the digital one I have doesn't have any of this type of stuff.

 

One of the inputs from the TRS to the PCM is open. I'd vote for a bad TRS.

In PARK, all four digital input (TR1-TR4) are supposed to be a logical "0" level. I'd suspect that one of the switches is open (TR3, probably) and that, when the shift selector is in the normal D/OD position, that particular switch is also open. Therefore, the PCM sees an invalid code and complains when the selector is in PARK but is perfectly fine when the shift lever is in the driving position that you've tested.

FWIW, I can pull Ford's manufacturer-specific codes with a $25 eBay Bluetooth adapter and a $10 Android app. The key is "manufacturer-specific" code support. I've also got Alex Peper's OBDII interface and software on my laptop that can read the supplemental systems also. Less than $250 spent on that one and I've owned it for more than 10 years.